Heater assemblies are used to create a generally flat temperature zones on substrates, onto which semiconductors are formed by metal organic vapor deposition methods.
Current prior art heaters used for heating substrates feature porous cast heater bodies having heater coils that are swaged into grooves. In some prior art heaters, heater cable is suspended in a pattern while a plate is cast, resulting in an embedded heater element that can have an uneven profile. The use of porous cast heater components can result in outgassing when subjected to typical vacuum semiconductor processing environments. Furthermore, the swaged construction commonly results in the distortion or warping of heater assemblies as they are operated at process temperatures.
S. Boldish and S. Ciofalo, Epitaxial Heater Apparatus and Process, U.S. Pat. No. 4,777,022 Oct. 11, 1988) disclose a chemical vapor deposition apparatus having a quartz envelope supporting a resistance heater. A core supports resistance heater windings. An alternative horizontal configuration includes a laminar flow head disposed at an angle to the horizontal.
J. Banker, Aluminum/Steel Transition Joint, U.S. Pat. No. 5,213,904 (May 25, 1993) discloses a transition joint between aluminum and steel comprising complex inter-layers of titanium and copper-nickel, formed by an explosive bonding process.
W. Blair, Method of Manufacturing Lightweight Thermo-barrier Material, U.S. Pat. No. 4,703,159 (Oct. 27, 1987) discloses a method of manufacturing thermal barrier structures comprising at least three dimpled cores separated by flat plate material with the outer surface of the flat plate material joined together by diffusion bonding.
W. Blair, Bi-Metallic Thermo-barrier Material and Method of Welding, U.S. Pat. No. 4,318,965 (Mar. 9, 1982) discloses the manufacturing of multi-layer, bi-metallic thermobarrier material utilizing combined brazing and diffusion bonding methods of joining together the components of the barrier material.
The disclosed prior art systems and methodologies thus provide heaters for semiconductor processing, and disclose some methods for providing bonds between dissimilar metals, but fail to provide a strong, homogeneous heater assembly that offers exceptional heat distribution and with minimal heat variation and distortion, which can be used in a vacuum environment without outgassing. The development of such improvements to a heater system would constitute a major technological advance.